Influence of BaO and MgO on viscosity, crystalline phase, and structure of CaO–Al2O3–10%SiO2–20%CaF2-based system

Abstract

In the current study, the low SiO2 mold flux for the continuous casting of the transformation-induced plasticity steel was studied to avoid the interface reaction between the dissolved aluminum in the molten steel and silica in the mold flux. The viscometer, Raman spectra, and X-ray disproportion were employed to study the viscosity, melt structure, and crystalline phase of the mold flux, respectively. The viscosity of the mold flux decreased with the replacement of MgO by BaO due to the balance of the melt structure and the precipitation phase. The aluminosilicate and silicate structures were depolymerized to simpler units with the replacement of MgO by BaO in the mold flux since a preference that Ba2+ tended to act as a charge compensator. The viscosity of the mold flux roughly increased with the addition of the total BaO and MgO content due to the formation of the MgAl2O4 phase in the pure liquid phase. The substantial precipitation of the MgAl2O4 phase in the liquid melt caused a sharp increase in the viscosity of the mold flux, which should be avoided by lowering the MgO content to less than 3 wt%.